Respected user, hi I evaluated your query thoroughly . * Stomach pain with blood in stool is not common at all. * This warrants underlying intestinal infection like colitis or else ; drug induced ;possible inflammatory bowel disease , bleeding gastric or duodenal ulcers & many other intra abdominal pathology like tumors etc . * Definite evaluations in the form of laboratory parameters , ultrasound of abdomen & pelvis, colonoscopy are vital to conclude the definite reason . Hope this helps you . Welcome for any further assistance . Thanks for using Healthcaremagic.com & giving me an opportunity to assist Regards dear take care.